Bloomberg: The Russian ex-con with a thriving banking business in Crimea

Woman carries a flag of Crimea after a rally marking the one year anniversary of annexation of Ukraine's Crimea peninsula, outside the Kremlin, in the back, in Moscow, Russia, Wednesday, March 18, 2015 (AP Photo)

As he tells it, he knows the tricks of the money launderer's trade. He was deported from the U.S. after tax-fraud convictions. He has served as an aide to the man suspected by U.K. authorities of poisoning former spy Alexander Litvinenko in London. Protection from the KGB's successor helped him fend off extortion allegations in Moscow.

Since his Genbank opened its first branch down the street from the main government offices in Crimea just two weeks after Russia's 2014 takeover of the Ukrainian peninsula, the bank has expanded to 175 branches to become No. 2 in the region. Early this year, regulators approved a 1.4-billion-ruble (USD 20 million) capital boost to help it keep up with the growth.

Another reflection of its prominence: the U.S. in December added Genbank to its list of Russian entities sanctioned for operating in the annexed territory.

"There are opportunities in Crimea that just aren't available on the mainland,"Dvoskin said in a recent interview in his Simferopol office, decorated with Russian Orthodox icons and a photo of President Vladimir Putin hanging above a lit candle.

It was "pure coincidence" that brought him to Crimea shortly before the Russian takeover. Enthusiasm about the "historic events" has kept him there to lead Genbank's expansion, he said.